Method for producing needled textile structures



June 1966 N. s. NEWMAN ETAL 3,255,509

METHOD FOR PRODUCING NEEDLED TEXTILE STRUCTURES F'iled Dec. 25, 19653,255,509 METHOD FOR PRODUCING NEEDLED TEXTILE STRUCTURES Nicholas S.Newman, Cambridge, and John F. Ryan, Walpole, Mass., assignors to TheKendall Company, Boston, Mass., a corporation of Massachusetts FiledDec. 23, 1963, Ser. No. 332,592 6 Claims. (Cl. 28-721) This inventionrelates to composite needle-laminated textile structures for interliningand insulating purposes; More particularly, it relates to laminates offiber to fabric, or three-component laminates of fiber-foam-fabric, ofsubstantial elastic conforrnability and high tensile strength.

3,255,509 Patented June 14, 1966 ice In general, the slack mercerizingprocess is effected by treating a cellulosic fabric with caustic ofmercerizing strength while the fabric is maintained substantiallywithout tension in either the filling direction, the warp direction, orboth. Shrinkage in the untensioned direction or directions results, theextent of the shrinkage being generally governed by the twist multipleof the yarns and by the cover factor of the fabric, which in turn isrelated to the size of the yarns and the number of yarns per inch. Thethus shrunken fabric is then washed free of caustic and dried under suchconditions as to retain a substanv tial part of the shrinkage impartedby theslack mercer- Composite laminated structures are known in which afibrous fleece is needled to a fabric base, or in which a layer ofelastomeric foam is sandwiched between the fibrous and the fabriccomponents to form a three-ply laminate. Laminates of the latter typeare disclosed in US. Patent 3,059,312, to Jamieson. However, prior artstructures of either the two-ply or vthe three-ply type are generallycategorized as inextensible, and though they may be flexible, theydisplay little or no elongation or recovery due to the dominance of theinextensible fabric base with which the foam andthe fibrous fleece arecombined. Such prior art needled laminates have been proposed for a widevariety of uses, such as floor coverings, insulating felts, papermakersfelts, and the like, where their non-elastic nature is not a criticaldeterrent to their use.

Attempts have been made to create inexpensive interlinings by needling afibrous fleece to a knitted fabric reinforcement, to provide someextensibility to the combination, but the effect of the needlingoperation almost invariably is to puncture some of the yarns of the knitfabric, with consequent ravelling, lack of support, and

local loss of fabric elongation and recovery where yarns have beensevered.

Similar considerations apply to the use in such an application of trulyelastic reinforcing fabrics-i.e., fabrics layers and without developingholes, runs, or fray in the fabric layer. Prior art laminates aredeficient in one or more of the above respects.

We have found that lining materials of excellent quality may be producedby needling together a fibrous fleece, and a woven fabric which has beentreated so that it is marked by a ready elongation or extensibility inthe warp or filling direction, or both. This assembly may also include alayer of foam, if recoverability and added insulating value are desired.This extensibility may conveniently be effected in a cellulosic fabric,for example, a cotton sheeting, print cloth, or Osnaburg, by a slackmercerization process in one or both directions, as set forth in anarticle entitled Special Elastic Propertiesof Cotton Yarn and ClothMercerized without Tension, by Goldthwait and Murphy, Textile ResearchJournal, pages 47-57, January 1955. The use of slack-mercerized fabricin the process of this invention has led to unexpectedly superiorresults, as set forth below.

izing process.

The relatively recent availability of solvent-resistant polyester foamshas created a great .deal of interest in the utilization of suchmaterials as thermally-insulating linings for garments, and/or shapinginterlinings for g'arments. However, the limited tensile strength ofunsup-' ported foams has required that-they bestrengthened by laminatingto a stronger element: hence, it is common practice to laminate togethera sheet of, say, polyurethane foam with a layer of fabric. A widevariety of woven or knitted fabrics may thus be combined with foam,either by a solvent-based adhesion process or by melting the surface ofthe foam to a plastic condition at or about the point of combination asdescribed in US. Patent 2,957,793 to J. W. Dickey. Such processes areexpensive, however, and their use is generally confined to applicationswhere the foam serves as interliner and the fabric is the outer orwearingv face of the garment.

In the utilization of laminates for interlining purposes, each elementin the combination plays a specific role. In the case of three-plylaminates, the foam contributes bulk, resilience, insulating value, andelastic recovery, combined with light weight. Used alone, however, foamis deficient in tensile strength, generally running'from 1.5 pounds to3.0 pounds periinch-wide strip inch thick, depending on quality. Theless expensive foams, though of good insulating properties, are low intensile strength, especially when needled to a fibrous fleece, and donot serve as a strong, durable lining material.

For esthetic reasons, as well as for added insulating value, it iscommon practice to needle a fleece or layer of fibers to foam forapplications of this nature. The fibrous layer imparts a rich textileappearance to the foam, and may be made to simulate a-pile fabric orfleece lining, or may be closely needled to resemble a suede.Additionally, the fiber layer protects the foam from the yellowing oraging which is characteristic of the effect of ultraviolet light onfoams. In general, however, foam-fiber needled combinations are lackingin sufficient tensile strength to be used above as garment linings, andare of practically unrestricted elongation: that is, the presence of thefibrous layer does not restrict the tremendous capacity for elongationof the foam.

To strengthen foam-fiber combinations, they are frequently combined witha woven textile fabric. This, however, not only leads to an inextensibleand non-comformable laminate in the case of conventional woven fabrics,but to a substantial decrease in the tensile strength of the fabric, asexplained below. 7 It is the essence of this invention that marked andunexpected improvements are effected in needled fiber-fabric orfiber-foam-fabric laminates if a slack-mercerized fabric capable ofsubstantial ready elongation of from say 15% to as defined hereinbelow,is used in place of conventional woven or knitted fabrics. the; two-plylaminate, a marked conformability under stress is realized. In the caseof the fiber-foam-fabric laminates, this same ready conformab-ility isaccompanied by substantially complete recovery when stress is released.Additionally, although the initial modulus of elongation In the case ofof either type of laminate of this invention is low, at or about thepoint at which the slack-mercerized fabric is extended to the count orto the area which is possessed before the slack mercerization process,there is a pronounced resistance to further deformation, so that bysuitable choice of slack-mercerized fabric, a laminate can be producedwhich has a built-in elongation limit. Such laminates, we have found,possess an unexpected resistance to delamination or separation of fiberfrom fabric, and to fiber shedding.

Finally, we have found that slack-mercerized fabrics survive thepuncturing effect of a needling operation to a surprising extent, with ahigh and unexpected preservation of their inherent tensile. strength, asset forth more fully hereinbelow.

It is a basic object of this invention to provide a conformable needledtextile laminate capable of substantial ready elongation but with abuilt-in elastic limit, said laminate simultaneously possessing asubstantial ultimate tensile strength. It is a further object of thisinvention to provide laminates of the above nature which are resistantto delamination, and which are further characterized by rapid andsubstantially complete elastic recovery from applied stresses.

The invention will be more clearly understood with reference to theaccompanying drawings, in which:

FIGURE 1 is a magnified cross-sectional view of a fiber-fabric laminateof this invention.

FIGURE 2 is a magnified cross-sectional view of a fiber-foam-fabriclaminate of this invention.

FIGURES 3 and 4 are representations, highly magnified, of single yarnloops and some of the fibers thrust therethrough, characteristic of thepebbled texture on the surface of the fabric layer employed in thisinvention, after needling.

FIGURE 5 is a perspective veiw, highly magnified, of a needle thrustthrough the yarns of a slack-mercerized fabric.

Slack mercerization of cellulosic fabrics, as described in theabove-cited Goldthwait article and in US. Patents 2,379,574 and2,404,837, is marked by a pronounced shrinkage of the fabric. If thefabric is held under warpwise tension in the process, the shrinkage, andsubsequent elongation potential, is across the filling direction. Sincemost textile operations of washing, drying, etc., exert warpwisetension, and since elongation in one direction makes a fabric suitablefor a majority of applications, slack-mercerized fabrics which arestretchable only in the filling direction are most readily made. It is,of course, possible to develop stretch in both warp and fillingdirections, and such a process is known in the art.

If the process is carried out on an open-meshed fabric such as surgicalgauze of 24 x 20 or 20 x 12 count, the shortening and kinking of theyarns tends to cause a series of twisted or kinked crunodal loopsbetween the yarn intersections, due to the freedom of movement of theyarns in open-meshed fabrics. Such behavior, characteristic of fabricsof a cover factor of 5 or less, imparts a pebbled appearance to thefabric surface.

In the case of more tightly woven fabrics, such as sheetings and printcloths, with cover factors of 8 and higher, the yarn span between yarncrossings is not long enough to allow the formation of a yarn loop orkink. The yarn retraction tendency in such cases is satisfied by theyarn assuming an exaggerated crimped or waved configuration, of anamplitude depending on the weave of the fabric and the severity of theshrinkage treatment. Such fabrics after slack mercerizing arecharacterized by a relatively smooth and even surface, free from thepebbly kinks associated with low-count slack-mercerized fabrics.

If a layer of fibers is needled into a conventional piece ofmedium-count fabric, such as a 64 x 60 print cloth or a 44 x 40sheeting, it is expected that a certain amount of yarn breakage willinevitably occur as the barbs or points of the needle engage the yarnsof the fabric. In a 64 x 60 print cloth made from 30s yarns in the warpand 40s yarns in the filling,-the spacing between warp yarns is of theorder of .008 inch, and between filling yarns. .010 inch. Needlescommonly used in needle looms range from .025 to .035 inch in diameter.Since the yarns in a conventional print cloth are relativelyinextensible, and since the points of a large number of needles in abank usually descend onto the fabric simultaneously, yarn breakage is aconcomitant damaging factor. Not only is the base fabric generallyweakened, but localized areas are developed where the adherent fibrouslayer is poorly supported, leading to material which is irregular intensile properties from point to point.

We have found that when a slack-mercerized fabric of a constructioncount similar to a conventional print cloth or sheeting is subjected toa needling operation to unite it to a layer of fibers, there is minimalyarn breakage, no formation of local weak spots, the strength of theneedled assembly is at least as great as the strength of. the unneedledbase fabric, and the fibrous layer adheres to the fabric with anunexpected tenacity. Such a structure is shown in FIGURE 1, wherein alayer of fibers 14 has been needled into a slack-mercerized fabric 10comprising warp yarns 13 and filling yarn 11, with the formation ofnumerous unbroken loops 16, which are stuffed with fibers, and whichimpart a pebbled texture to the backface of-the fabric.

A single loop 16 is shown in magnified form in FIG- URES 3 and 4. Theyarn 11, when in the unneedled slack-mercerized fabric, may beconsidered to have been disposed horizontally. The thrust of animpinging needle point carrying a burden of fibers 18 has displaced theyarn 11 into a loop form 16, with the fibers 18 of the fibrous layerinterlocked with the yarn loop. The loop may be a plain bight, as inFIGURE 3, or may be crunodal, as in FIGURE 4. Both types of loop are metwith in this invention, the crunodal type being presumably due to thetwisting tendency of slack-mercerized yarns. fibers 18, in passingthrough the loop 16, pass on both sides of the yarn 11 to extendoutwardly from the loop.

Apparently the reaction of the crimped yarns of a slack-mercerized printcloth to the direct thrust of a needle barb is one of elongation, withthe result that the -crimp is locally removed from a very short lengthof yarn and an open yarn loop is formed protruding from the face of thefabric. If the needle barb impingement is glancing rather than direct,the needle thrust has a lateral component, and the loops formed extendat an angle which is less than perpendicular to the face of the fabric.Loop orientations are thus randomized, but the important considerationis that they remain closed loops, the yarn is not ruptured, .and uponthe application of stress to the laminate it is found that the basefabric has not been appreciably weakened as a conventional fabric ofcomparable construction would have been.

Not all of the needle thrusts in the action of a bank of needles willresult in direct impingement on a yarn, with loop formation. Themajority of the thrusts will carry theneedle, with its burden of fibers,through the interstices formed by the warp and filling yarns. This isshown in FIGURE 5, where a needle 20 with a barb 17 is thrust betweenthe warp yarns 13 and the filling yarns 11 of a slack-mercerized fabric,the fibers carried by the needle being indicated by the fibrous bundle19. The yarns 11 and 13 of the slack-mercerized fabric have a highdegree of elasticity compared with the yarns of a conventional fabric.They are therefore capable of substantial elongation, and tend torespond to the thrust of the needle-point by elastic deformation ratherthan by permanent lateral displacement. FIGURE 5 illustrates this typeof elastic deformation, wherein the yarns 11 and 13 bend around theneedle shank as the needle passes through the fabric. This elasticdeformation is recoverable, so that upon the removal of the needleshank, the

It will be noted in FIGURES 3 and 4 that the yarns 11 and 13 willcontract, narrowing the opening createdby the needle shank, and lockingthe fibrous bundle 19 to the fabric. In the practise of this inventionit has been observed that when a layer of fibers ofa specific type isneedled into a slack-mercerized fabric, the bond between fibers andfabric is substantially stronger than that resulting from the needlingof a similar layer of fibers to a non-slack-mercerized fabric ofcomparable construction. Therefore the laminates of this invention haveincreased resistance to delamination and to fiber shedding, oftenallowing the omission of the back-coating operations conventionally usedto provide increased anchorage of fiber to fabric.

A further consequence leading to an increased fiberand 4. In the processof stretching a slack-mercerized fabric to which a layer of fibers hasbeen needled, the loops 16 of FIGURES 1 through 4 tend to disappear. Dueto the peculiar nature of the yarns in a slack-mercerized fabric, loopsformed from such yarns are under stress, and have the potential toreturn to the plane of the fabric since they are still inherentlyelastic. It will be noted that when a loop is formed, as shown inFIGURES 3 and 4, the fibers 18 pass along both sides of the yarn 11. Theelastic retraction of the loops 16, brought about gradually throughrepeated small deformations of the laminate when used as a conforminginterliner, means that the loops gradually work themselves down into theface of the fabric, whereby the fibers passing on both sides of the yarnloop are uniquely and firmly interlocked into the fabric.

The following example will illustrate one method of making the productof this invention.

EXAMPLE 1 v A 42 x 36 bleached cotton sheeting was slack mercer'ized,allowing both-warp and filling shrinkage. The final count of theslack-mercerized fabric was 60 x 54, the tensile strength was 24.2pounds per inch-wide strip in the warp direction and 14.1 pounds in thefilling, and the elongation at break was 35% in the warp and 64% in thefilling direction, the ready elongation, realized by moderate stretchingby hand, being in excess of 25% in the warp and 50% in the filling.

By ready elongation is meant the elongation that may readily be realizedwhen the elasticized fabric is pulled out by hand to its approximateoriginal dimensions, with a corresponding decrease in the excess crimpwhich the process has induced into the yarns. For standardizationpurposes, ready elongation is herein defined as the elongation realizedwhen a weight of five pounds is applied to a strip of material one inchwide. It should be realized that conventional, non-slack-mercerizedfabrics will show a certain amount of elongation when tested for tensilestrength. The total elongation, or elongation at break of aslack-mercerized fabric is the sum of the elongation built into thefabric by shrinkage plus the normal elongation at break displayed by thefabric before the slack mercerizing process, and is generallysubstantially higher than what we have here termed ready elongation.

The slack-mercerized fabric was laminated to a fibrous wool fleeceweighing 100 grams per square yard by passing the combination twicethrough a Hunter needle loom with pitch and rate of advance set so thateach square inch of fabric was subjected to 184 needle impacts persquare inch on each pass. The tensile strength of the needled laminatewas 24.8 pounds in the warp and 21.7 pounds in the filling, while theelongation was 33.7% in the warp and 56% in the filling, again withready elongation of over 25 warp, 50% filling.

By the needling process, a portion of the fibers of the fleece wereforcibly reoriented in a direction normal to their substantiallyhorizontal orientation and were thrust through the fabric layer tobecome intimately interlocked with and adherent to the fabric by apenetration-in-depth through the interstices of the fabric.

The slack-mercerized fabric, after the needling operation was marked bya series of pebbly yarn loops or bi-ghts, where the yarns had beenpushed out of the plane of the fabric. A S-inch square, containing about300 warp yarns and 270 filling yarns, was carefully ravelled out, yarnby yarn, to detect yarn breakage. A total of 4 yarn breaks, out of 570yarns was found. This remarkably low incidence of yarn breakage, of lessthan 1%, is indetectable in effect on the fabric tensile strength.Moreover, when a set of 4 adjacent Warp yarns was deliberately severedand the fabric'was stressed, it was noted that there was no propagationof the discontinuity thus created. The kinky, crirnped nature of theyyarns which had been slack-mercerized to a large extent prevented yarnslippage in the vicinity of the cut ends, the discontinuity did notenlarge, and the cut yarns served as load-bearing members due to theirintense crimp-induced interengagement with the filling yarns. Thisbehavior is in sharp and unexpected contrast to the behavior ofconventional woven fabrics of comparable count, and in particularcontrast to the behavior of knit goods.

When the product of Example l was stretched 25% in the filling direction(45% of its ultimate elongation), recovery was Repeated cycling,however, gave increasingly lower recovery values. The product issuitable for use in applications where a high degree of elongation andconformability are desirable, as in shoulder padding for garments.

EXAMPLE 2 A 44 x 40 bleached cotton sheeting was s'lack-mercerized,allowing both warp and filling shrinkage. The final count of the fabricwas 58 x 51, and it had a ready elongation of 31% in the warp directionand 27% in the filling direction, elongations at break being 37% in thewarp and 40% in the filling. Tensile strengths were 42 pounds in thewarp and 39 pounds in the filling.

Using the same needle loom settings as in Example 1, thisslack-mercerized fabric was needled to a layer of carded Dynel fibers(Union Carbide) weighing 80 grams per square yard. The tensile strengthof the needled laminate was 41 pounds in the warp and 33 pounds in thefilling, per inch wide strip, with elongations of 24% in the warpand 33%in the filling, with over 15% ready elongation in each direction.

When 395 -yarns,*equally divided between warp and EXAMPLE 3 Example 2was duplicated exactly except that a nonslack-mercerized sheeting of 56x 48 count was used. The total elongation at break was only 11% warp,13% filling, with negligible ready elongation. When warp and 140 fillingyarns were ravelled from this fabric, a total of 25 yarn breaks, or 9%was found.

In certain applications for lining or insulating material, it isdesirable that elongation be combined with elastic recovery. Sinceslack-mercerized fabrics are characterized by high elongation buteventual loW recovery on repeated cyclic loading, we provide a trulyelastic lining or insulating material by combining with the fiber-fabriclaminate of Example 1 a layer of foamed elastomeric material, as inExample 4.

EXAMPLE 4 v A three-component laminate, as illustrated in FIG- .URE 2,was prepared by needling a carded fleece of Dynel fibers weighing 80grams per square yard, through a layer of elastorneric foam-12 and intoa layer of slack-' The foam was a polyester foam, Type 5200, inch'thick, a product of General Foam Corporation. Alone, it has anelongation of 300% and a tensile strength at break of 2.25 pounds perinch wide strip. The three components, superimposed as shown, wereneedled together with the same machine settings used in Example 1. Thefinished laminate had a tensile strength of 29 pounds in the warpdirection and 28 pounds in the filling direction, with a 31% warpelongation and 56% filling elongation, over 25% of the warp elongationand 50% of the filling elongation being readily realized byhandstretching. By the needling process, a portion of the fibers of thecarded fleece were forcibly reoriented in a direction normal totheirsubstantially horizontal orientation and were thrust through thelayer of foam and through the fabric layer, so that the three elementsof the laminate were intimately interlocked by the penetrationin-depthof some of the fibers of the fleece through the foam and through-theinterstices of the fabric.

When elongated 25%, the material recovered over 90% of its originallength upon release of the load. Unlike the material of Example 1,however, the laminate of Example 2 recovered to the same degree afterrepeated elongation and relaxation cycling. It has a high thermalinsulating value, and is suitable for use in garments where the liningis subjected to repeated stresses followed by stress release, as itrecovers its dimensions readily and repeatedly.

A wide variety of cellulosic fabrics may be slackmercerized to yieldstretchable, readily conformable base fabrics suitable for use in thisinvention. The choice of fabric will be dictated by the particular useto which the laminate is to be put. In general, as we have noted above,fabrics of the gauze" category, having counts from 14 x to 32 x 28, andcomposed of 30s and 40s yarns, will be of such an open weave that acrepe-like pebble is formed by spontaneous looping of the yarns betweenyarn interstices. To some extent, the cover factor of the fabric,defined as the number of yarns in a warp or filling set divided by thesquare root of the yarn size, on the cotton system, is an indication ofthe amount of open space in a fabric. This in turn is an index of thefreedom of movement of individual yarns to respond to the shrinkingeffect of the slack mecerizing process, neglecting the influence ofweave structure. The following Table I lists the properties of a varietyof slack-mercerized fabrics, all of which were prepared by passing thebase fabrics through a solution of sodium hydroxide at 0 C. whileallowing substantially complete fabric relaxation in warp and filling.

The apparatus used comprised an open tray of caustic soda and a conveyorbelt for removing the shrunken fabrics, as described in the UnitedStates Patent 2,688,864, of September 14, 1954, to H. A. Secrist,together with tensionless rinsing and drying equipment.

The influence of cover factor may be seen from the above table. Inrelatively open fabrics, such as print cloth and sheetings with coverfactors of about 10, a ready elongation of around 30% may be realized inboth warp and filling. In a fabric like the 112 x 56 broadcloth,however, the warp cover factor is 18. This means that the warp yarns areso close together that only 8% shrinkage took place across the fillingdirection or width of the fabric, it being understood that the warpcover factor affects the filling direction shrinkage and the fillingcover factor affects the warp shrinkage. In general, we find thatfabrics with a cover factor of 8 to 15 yield after slack mercerizingfabrics with ready elongations of from 40% down to 15%, and such a rangeis preferred for interlining use. For many purposes, elongation in onlyone direction is necessary, which may be accomplished by using normalprocessing tensions in, for example, the warp direction, while allowingthe filling to contract.

The fibers employed in the preparation of the laminates may be naturalor synthetic. Preferably they are of textile length-that is, long enoughto be formed into a fleece or batt by conventional dry-assemblingtextile equipment such as cards, garnetts, air-lay machines, and thelike. In the case of synthetic fibers a convenient length is fromone-half inch to about one and one-half inches: the natural wool fibersof Example 1 were several inches long.

It will be obvious to those skilled in the art that modifications of theabove-described invention may be made without departing from the spiritthereof. Thus, a layer .of fibers may be needled into both sides of aslackmercerized fabric, or a multiplicity of layers of fiber, fabric,and foam may be needled together, subject only to the penetration limitsof the needles in the loom.

Having thus described our invention, we claim:

1. In a process for enhancing the tensile strength and delaminationresistance of fabric laminates comprising needling at least one layer oftextile-length fibers into a woven cellulosic fabric base, theimprovement which comprises shrinking the woven cellulosic fabric baseprior to the needling operation by a slack-mercerizing process, saidshrinkage being such as to allow at least 15% subsequent elongation inat least one direction of said needling at least one layer of foam andat least one layer of textile-length fibers into a woven cellulosicfabric base, the improvement which comprises shrinking the wovencellulosic fabric base prior to the needling operation by aslack-mercerizing process,

said shrinkage being such as to allow at least 15% subsequent elongationin at least one direction of said fabric,

whereby the resistance of the yarns of the woven cellulosic fabric tobeing severed by the needling operation is increased.

5. The method of claim 4 in which the slack mercerizing and shrinkage ofthe cellulosic fabric is carried out in the filling direction.

6. The method of claim 4 in which the cover factor of the base fabricbefore slack mercerizing is between 8 and 15.

(References on following page) 9 References Cited by the Examiner3,085,309 4/1963 Olson 28722 X 3,090,101 5/1963 Chagnon 28-'72.2 UNITEDSTTES PATENTS 3,123,892 3/1964 MacMillan et a1 28722 10/1932 T11R38 28762 1 3 181 2 5 5 DONALD W. PARKER, Primary Examiner.

0 t Walt Mersereau M- Examiner.

9/1960 Hofiman 2872.2 X A. I. SMEDEROVAC, L. K. RIMRODT, 10/1962Jamieson 28722 X Assistant Examiners.

1. IN A PROCESS FOR ENHANCING THE TENSILE STRENGTH AND DELAMINATIONRESISTANCE OF FABRIC LAMINATES COMPRISING NEEDLING AT LEAST ONE LAYER OFTEXTILE-LENGTH FIBERS INTO A WOVEN CELLULOSIC FABRIC BASE, THEIMPROVEMENT WHICH COMPRISES SHRINKING THE WOVEN CELLULOSIC FABRIC BASEPRIOR TO THE NEEDLING OPERATION BY A SLACK-MERCERIZING PROCESS, SAIDSHRINKAGE BEING SUCH AS TO ALLOW AT LEAST 15% SUBSEQUENT ELONGATION INAT LEAST ONE DIRECTION OF SAID FABRIC, WHEREBY THE RESISTANCE OF THEYARNS OF THE WOVEN CELLULOSIC FABRIC TO BEING SEVERED BY THE NEEDLINGOPERATION IS INCREASED.